Fan equipment



Nov. 16, 1965 s. H. DOWNS 3,217,976

I FAN EQUIPMENT Filed April 20, 1964 3 Sheer.s-Sheetv 1 INVENTOR- SfWELLH DOW/V5 A TTOEWEHS S. H. DOWNS Nov. 16, 1965 FAN EQUIPMENT 3Sheets-Sheet 2 Filed April 20, 1964 INVENTOR. .SEWL'LZ H. DOW/V5ATTOPNEHS Nov. 16, 1965 Filed April 20, 1964 H. DOWNS FAN EQUIPMENT 3Sheets-Sheet 3 INVENTOR.

SEWEZZ H. DOW/V5 United States Patent Office 3,217,976 FAN EQUIPMENTSewell H. Downs, Kalamazoo, Mich., assignor to Clarage Fan Company,Kalamazoo, Mich., a corporation of Michigan Filed Apr. 20, 1964, Ser.No. 361,053 5 Claims. (Cl. 230-427) This application relates in generalto an in-line fan construction utilizing a centrifugal impeller and,more particularly, to an improved type of in-line fan includingstructure for increasing the output efiiciency of the impeller therein.

It is well known that the performance of a centrifugal impeller in theaverage installation is substantially less than it theoretically couldbe, if the turbulent conditions, hence losses, which develop in theregion of the inlet side of the impeller, could be avoided. Numerousattempts have been made to reduce such tubulence, and an example of oneattempt is disclosed in Patent No. 3,011,693, which is assigned to theassignee of this application. However, the apparatus in Patent No.3,011,693 which is designed to control or improve the flow of the inletboundary layer, is not applicable in this instance because of thecompletely different type of discharge arrangement.

While studying the performance of a centrifugal impeller within thehousing of an in-line fan construction, it was found that the dischargefrom the impeller divided, near the inlet side of the impeller into twodiverging flow paths which, at one stage, move in substantially oppositeaxial directions. That is, a relatively large volume of the dischargedair is moved by the impeller first radially and then axially toward andthrough the discharge end of the housing. A smaller, but substantial,amount of the air discharged from the impeller moves in the oppositedirection and forms a natural vortex or whirl around the inlet cone andadjacent side of the wheel, the inlet normally in the direction ofrotation of the wheel. Thus, in the zone between the two separating flowpaths, which has a substantially V-shaped cross section there presentlyexists a very turbulent condition which as well understood by engineers,produces costly losses of energy and inefi'icient performance.

During the course of examining carefully the foregoing conditions, itwas found that a plurality of spaced flaps disposed at selectedpositions within the turbulent, annular zone around the inlet side ofthe centrifugal impeller materially reduced such turbulence and therebyincreased the output performance of the impeller, hence of the in-linefan construction. That is, higher pressures and more c.f.m. could beproduced with the same installation using the same amount of horsepowerinput, merely by placing the small flaps or their functional equivalent,in said tubulent annular zone.

In previous experiments conducted in this type of fan construction, itwas found that vanes placed in the zone adjacent the peripheral surfaceof the inlet cone, hence adjacent the inlet side of the impeller, woulddisturb the natural vortex and would actually reduce the performance ofthe impeller. Thus, it was not reasonable to expect that a plurality ofrelatively small flaps or blades located in the annular zone ofturbulence, between the two flow paths, would have a contrary, indeedfavorable, effect upon the performance of the unit.

Accordingly, a primary object of this invention has been to provide anin-line fan construction including a centrifugal impeller andappropriate apparatus for improving the output performance of suchimpeller without making material changes in the construction.

A further object of this invention has been the provi- .sion of animproved in-line fan construction, as aforesaid, which can be adaptedfor direct drive operation or 3,2l7,976 Patented Nov. 16, 1965 beltdriven operation, and which can be adapted for use with inlet vanecontrol, such as the Clarage Vortex Control, or outlet damper control.

A further object of this invention has been the provision of an improvedin-line fan construction, as aforesaid, including discharge turbulencecontrol mechanism which can be used with a variety of centrifugalimpellers capable of use in an in-line fan construction.

A further object of this invention has been the provision of an in-linefan construction, as aforesaid, which can be made at substantially thesame cost as existing in line fan constructions, and which is capable ofbetter performance with a lower operating cost than existing in-line fanconstructions of a similar type for the same or similar purposes.

Other objects and purposes of this invention will become apparent topersons familiar with this type of equipment upon reading the followingspecification and examining the accompanying drawings, in which:

FIGURE 1 is a side elevational view of an in-line fan constructionembodying the invention.

FIGURE 2 is a sectional view taken along the line II--II in FIGURE 1.

FIGURE 3 is a sectional view taken along the line III-III in FIGURE 2.

FIGURE 4 is a sectional view taken along the line IVIV in FIGURE 2.

FIGURE 5 is a sectional view taken along the line VV in FIGURE 2.

FIGURE 6 is an enlarged sectional view substantially as taken along theline VIVI in FIGURE 1 and including a control mechanism which can beused to adjust simultaneously the angular positions of the flaps.

FIGURE 7 is a fragment of FIGURE 2 showing a modified flap construction.

FIGURE 8 is a sectional view taken along the line VIII-VIII in FIGURE 7.

FIGURE 9 is a fragment of FIGURE 2 showing a modified constructionincluding an inlet vane control.

FIGURE 10 is a fragment of FIGURE 2 showing an alternate drivemechanism.

For the purpose of convenience in description, the terms inlet orupstream and outlet or downstream" will have reference, respectively, tothe left and right ends of the in-line fan construction, as appearing inFIGURES 1 and 2. The terms inner, outer and words of sim ilar importwill have reference to the geometric center of said in-line fanconstruction and parts thereof.

General construction The objects and purposes of this invention,including those set forth above, have been met by providing a fanconstruction including a cylindrical housing which is connectible at theopposite ends thereof to cylindrical ducts .or the like for the purposeof selecting the source from which air is drawn and the zone into whichthe air is moved by the fan construction of the invention. A centrifugalimpeller is rotatably supported concentrically within the housing bybearing means disposed within an annular shell which extends downstreamfrom the impeller. An inlet cone is preferably arranged to communicatewith the inlet side of the impeller, and curved, air straightening vanesare provided for their conventional purposes downstream of the impellerand also to support the annular shell.

A plurality of flaps are mounted upon the inner surface of the housingat uniform intervals therearound so that they extend toward, but arespaced a substantial dis tance from, the inlet side on the impeller. Theflaps are arranged and located so that they substantially increase theperformance of the impeller when it is rotated at a conventional speed.

The in-line fan assembly It) (FIGURES 1 and 2) comprises a substantiallycylindrical fan housing or casing H which preferably has exteriorannular flanges 12 and 13 secured to or integral with the opposite axialends thereof for the purpose of connecting said housing to similarflanges 16 and 17 on inlet and outlet ducts 18 and 19, respectively, ina conventional manner. The fan housing 11 has at its inlet end anannular end wall 22 having an integral, inwardly extending andconverging, inlet cone 23 defining an inlet opening 24.

An annular shell or wall means 26 (FIGURE 2), which may be cup-shaped,is concentrically disposed within the housing 11 and spaced from theinlet cone 23 a distance approximately slightly greater than the axialextent of the centrifugal impeller 27. The shell 26 has a substantiallyradially disposed end wall 28 at the upstream end thereof and aperipheral wall 29 which is concentric with, spaced from and divergesdownstream with respect to the inner surface 32 of the fan housing 11.The upstream end of the peripheral wall 29, which merges by an arcuatesurface with the end wall 28, is preferably somewhat larger in diameterthan the diameter of the adjacent back plate or rear shroud 33 on theimpeller 27.

The shell 26 (FIGURE 2) is supported upon and within the fan housing 11by a plurality of spaced and curved air-straightening vanes 34 which aresecured to and extend between the peripheral wall 29 and the innersurface 32 of the fan housing 11 near to, but spaced from, the upstreamend of said shell. A plurality, such as 3, support rods 36 (FIGURE 2)are secured to and extend between the shell 26 and the housing 11,preferably near the downstream end thereof, if they are necessary. Theupstream ends of the vanes 34 are preferably curved away from thedirection of the circumferential movement of the impeller, as indicatedby the arrow W in FIGURE 3. This curvature in the vanes 34 is carefullypreselected in terms of the characteristics of the impeller and itsrotational speed so that the upstream edge portions of the vanes 34 areapproximately parallel with the movement of the air discharged by theimpeller 27 as it meets the vanes 34. Thus, a minimum of loss isexperienced by the straightening operation performed by the vanes 34,whereby the air departs from the downstream edges of the vanes 34 in adirection substantially parallel with the central axis of the fanhousing 11.

The amount of divergence between the housing 11 and shell 26 in thedownstream direction is approximately 7 degrees in this particularembodiment. It has been known in the past that a 7 degree angle ofdivergence will minimize losses due to turbulence produced by skin orboundary layer friction without producing corresponding losses due toseparation of the air being moved. However, insofar as I am aware, itwas not known that this angular relationship would also apply where theair is moved into an annular passageway, or where such air is beingdischarged with a major circular component of movement in a directiontransversely of the lengthwise extent of the diverging passageway. Afterexperimentation with different angular relationships, it was found thatthe 7 degree angular relationship is at least highly satisfactory withthe improved construction embodying the instant invention.

A pair of bearing supports 37 and 38 (FIGURE 2) are mounted within andextend substantially diametrically across the shell 26, hence theperipheral wall 29 thereof. A pair of bearings 41 and 42 are mountedupon the supports 37 and 38, respectively, preferably so that they areconcentric with the central axis of the shell 26. The bearing 41 isadjacent the end wall 23 which is secured to the support 37 by thebrackets 43 and 44 (FIGURE A shaft 46 (FIGURE 2) is rotatably supportedby the bearings 41 and 42 so that one end thereof extends through acentral opening 47 in the end wall 28 for coaxial connection to the hub48, which is secured to the back plate 33 of the impeller 27 in asubstantially conventional manner. The other end of the shaft 46supports a pulley 51 which is connected by the belt 52 to the pulley 53on the shaft 54 of the motor 56.

The peripheral Wall 29 of the shell 26 and the fan housing 11 areprovided with openings 57 and 58, respectively, which are interconnectedby a sleeve 59 through which the belt 52 extends between the pulleys 51and 53. The mot-or 56 is mounted upon the external surface of the fanhousing 11 adjacent the opening 58.

As an alternate construction, the motor 56 may be mounted, as shown at56a in FIGURE 10, within the shell 26 upon the support 37 so that themotor shaft extends through the opening 47 and thereby directly supportsthe impeller 27.

The impeller 27, in this particular embodiment of the invention, has aninlet ring or intake shroud 62 which converges away from the back plate33 to define an inlet opening 63. In this embodiment, the small end ofthe ring 62 is slightly larger than, and is telescoped over, the smallend of the inlet cone 23 in a substantially conventional manner.

A plurality of blades 64, which are arranged and constructed in thisembodiment to provide a nonoverloading characteristic, are secured toand extend between the peripheral portions of the inlet ring 62 and theback plate 33, also in a substantially conventional manner. The impelleror wheel 27, which is substantially spaced from and concentric with theinner surface 32 of the fan housing 11, is preferably spaced somewhatfrom the shell 26.

A plurality of flaps 66 (FIGURES 2 to 5, inclusive), which arepreferably fiat and thin, are mounted upon the inner surface 32 of thehousing 11 preferably in radial alignment with the radially outer edgeportion 67 of the inlet ring 62. Said flaps 66 are preferably ofsubstantially uniform size and shape, they are preferably uniformlyspaced around the inner surface 32 between two parallel planes disposedon opposite sides of said outer edge portion 67, and they preferablyextend substantially radially inwardly from said housing 11 about halfthe distance between the housing 11 and the impeller 27. However, itwill be recognized by persons skilled in this field that, depending uponthe specific structural and operating characteristics of the particulartype of contrifugal impeller 27 used in any given installation, thesize, shape, radial extent and precise axial locations of the flaps 66,with particular respect to the location of the impeller 27, may bevaried somewhat without departing from the scope of the invention.

In a preferred embodiment, the flaps 66 are secured to radiallyextending pins 68 (FIGURES 2 and 6) each of which supports externally ofsaid housing 11 a crank 69. The several cranks 69 may in turn beconnected to a control ring 72 which encircles the fan housing 11adjacent said pins 68. An annular guide member 73 may be secured uponthe fan housing 11 adjacent the control ring 72 for the purpose ofretaining and guiding the movement of, the ring 72. Any type of manuallyoperable linkage, not shown, may be utilized to effect rotationalmovement of the ring 72, whereby the flaps 66 are simultaneously rotatedaround radii of the housing 11.

It has been found through experimentation that the flaps 66 operateefliciently with the type of construction and impeller disclosed hereinwhen they are pivoted around their pins at a slight angle (FIGURE 3),such as from about 15 to about 35, to a plane including the axis oftheir respective pin and the impeller. In a preferred embodiment, thedownstream edges of the flaps 66 were ahead of their upstream edges, inthe direction of movement of the periphery of the wheel 27 as identifiedby the arrow W in FIGURE 3, and the above-mentioned angular relationshipwas set at 25 degrees.

While the number of flaps 66 may be varied over a substantial range,depending upon the size and other characteristics of the fan assembly10, it has been found that a fan assembly of average size operateseffectively with 16 flaps 66.

However, it has been found that quantities of flaps from less than 16 upto as many as 32 can be used effectively and, although a certain numberof said flaps may operate most effectively under specific conditions,any quantity of flaps within this approximate range materially improvesthe performance of the fan assembly over such performance where thereare no flaps at all.

Operation When the impeller 27 is rotated by the shaft 46 in response toenergization of the motor 56, air is drawn through the inlet come 23 andinlet ring 62 and thereafter discharged radially by the blades 64 in asubstantially conventional manner. That is, a major portion of the airor other fluid discharged by the impeller flows downstream between thecasing 11 and the shell 26, and a minor portion of such air flows intothe swirl chamber encircling the inlet ring 62 and inlet cone 23.However, the flaps 66 materially reduce the turbulent conditions whichpreviously existed in the zone occupied by said flaps between thedivergent paths of air flow emanating from the impeller adjacent theinlet ring 62. Much if not most of this turbulent air is now induced bythe flaps 66 to join with the major air flow toward the discharge end ofthe fan housing 11, whereby the performance of the fan assembly 10 isincreased without increasing the power input.

At the same time, the flaps 66 do not disturb the natural vortex whichroatates with and adjacent the inlet ring 62 and around the inlet cone23. By appropriate movement of the control ring 72, the angularpositions of the flaps 66 can be adjusted if the need should arise.However, under most circumstances the flaps 66 will be fastened in theiroptimum positions when the fan assembly is manufactured, and no furtheradjustment will be required.

As illustrated in FIGURES 7 and 8, a modified fan assembly 80 comprisesa fan housing 81 in which an impeller 82 is rotatably supported insubstantially the same manner set forth above with respect to the fanassembly 10. However, in the fan assembly 80, the purposes of theinvention are achieved by concentrically supporting a substantiallyannular rim 83 in spaced relationship within the housing 81 by means ofthe plates 84. In this particular embodiment, the plates may besubstantially parallel with a plane including the rotational axis of theimpeller 82, or they may be disposed at a slight angle to such a plane,as discussed above with respect to the flaps 66. However, the number ofplates 84 can be less, where the rim 83 is provided, than the number offlaps 66 without the rim. In this regard, it has been found that,depending upon the diameter of the housing and impeller of the fanassembly involved, the number of plates 84 required may vary, as in thecase of the number of flaps 66.

In general, it has been found that the rim 33 should be disposed betweentwo parallel planes substantially perpendicular to the rotational axisof the impeller 82 and located in approximately the same positions asthe two planes between which the flaps 66 extend. That is, such planesare preferably located on opposite sides of the peripheral edge of theinlet ring 85.

The modified construction shown in FIGURE 9 illustrates the use of aninlet vane control 90 within an inlet cone 91 adjacent an impeller 92,and these latter two parts may be substantially identical with the cone23 and impeller 27, respectively. By means of the inlet vane control 90,which may be of a substantially conventional type, the performance,hence the output, of the associated fan assembly may be eflicientlycontrolled.

Although particular preferred embodiments of the invention have beendisclosed above for illustrative purposes, it will be understood thatvariations or modifications of such disclosure, which come within thescope of the appended claims, are fully contemplated.

What is claimed is 1. A fan construction comprisingz' a substantiallycylindrical housing having a central inlet opening at one end and anannular discharge opening at the other end, said discharge end beingaxially spaced from said inlet opening;

a centrifugal impeller disposed within said housing, said impellerhaving an arcuate intake shroud communicating with the central intakeopening and defining a forward swirl chamber closed at the said one end,the outer periphery of said intake shroud being radially spaced inwardlyof the cylindrical wall of the housing, said impeller having a rearshroud axially spaced from said intake shroud and having an outerperiphery spaced radially inwardly from said wall of the housing;

blades supported between said shrouds and having outer periphery edgesextending between. the shrouds adjacent the periphery thereof;

annular wall means supported within said housing and spaced radiallyinwardly from the cylindrical wall and extending axially rearwardly fromadjacent to said rear impeller shroud, said annular wall means and saidcylindrical Wall defining an axially extending chamber terminating insaid discharge opening;

shaft means and means supporting shaft means within said housing, saidshaft means rotatably supporting the impeller;

means on said shaft means to rotate said impeller whereby thecentrifuged fluid engaging said cylindrical wall of said housing dividesinto a major portion flowing into said annular chamber and a minorportion flowing into said swirl chamber;

said cylindrical housing wall having a plurality of short, substantiallyflat and substantially radially inwardly extending flaps mountedthereon, each of said flaps having a free inner edge that terminatesspaced radially outwardly of the blades outer edges, each of said flapshaving a pair of axially spaced end portions one thereof extending intosaid swirl chamber and the other portion extending only over that portion of the outer edges of the blades adjacent the intake shroud, saidflaps being so positioned to reduce turbulence in the zone of separationof the centrifuged fluid as it flows into said swirl chamber, and intosaid annular chamber from the zone of separation of said major and minorportions of fluid flow.

2. A fan construction according to claim 1, wherein said annular wallmeans diverges with respect to said wall of said housing away from saidimpeller at an angle of from 5 to 10;

wherein said annular wall means is mounted coaxially within saidcylindrical wall means by a plurality of elements secured to andextending between said housing and said annular wall means at intervalscircumferentially thereof;

wherein said annular wall means has an annular end wall adjacent to,spaced from and substantially parallel with said rear shroud; and

wherein said flaps are of uniform size and shape, each flap beingpositioned at an angle of from 55 to 75 with respect to a planeperpendicular to the rotational axis of the impeller and passing throughsaid flaps, the edges of said flaps nearest said annular wall meansbeing ahead of the opposite edges of said flaps in the direction ofrotation of said impeller.

3. A fan construction according to claim 1, wherein a cylindrical ringis secured to said inner edges of said flaps and extends axially betweentwo planes substantially defined by the axial edges of said flaps, saidring being spaced radially outwardly from the outer peripheral edge ofsaid impeller.

4. A fan construction according to claim 1, wherein said flaps are ofuniform size and shape and are disposed at substantially uniformintervals circumferentially of said housing;

wherein each of said flaps includes means pivotally supporting each flapfor movement around an axis extending radially of said impeller; andcontrol means mounted upon said housing and connected to each of saidflaps for effecting simultaneous pivotal movement of said flaps aroundtheir respective axes. 5. A fan construction according to claim 1,comprising: bearing means mounted upon and within said annular Wallmeans and rotatably supporting said shaft means; an electric motorhaving a shaft and being secured upon the outside of said housing; andmeans defining openings through said Wall means and said housing inradial alignment between portions of said shaft means and said motorshaft, said means on said shaft means comprising pulley and belt meansconnecting said motor shaft to said shaft means.

References Cited by the Examiner UNITED STATES PATENTS Davidson 230-127Lamontagne 23 0120 Schetzel 230--117 Kice 230114 McMahan et al 230125Alford 230122 Forrest 103-97 Taylor 230-114 Hemsworth 230-114 Benoit230-117 Carlson 230134.45

FOREIGN PATENTS France.

Great Britain.

20 KARL J. ALBRECHT, Primary Examiner. JOSEPH H. BRANSON, JR., Examiner.

1. A FAN CONSTRUCTION COMPRISING: A SUBSTANTIALLY CYLINDRICAL HOUSINGHAVING A CENTRAL INLET OPENING AT ONE END AND AN ANNULAR DISCHARGEOPENING AT THE OTHER END, SAID DISCHARGE END BEING AXIALLY SPACED FROMSAID INLET OPENING; A CENTRIFUGAL IMPELLER DISPOSED WITHIN SAID HOUSING,SAID IMPELLER HAVING AN ARCUATE INTAKE SHROUD COMMUNICATING WITH THECENTRAL INTAKE OPENING AND DEFINING A FORWARD SWIRL CHAMBER CLOSED ATTHE SAID ONE END, THE OUTER PERIPHERY OF SAID INTAKE SHROUD BEINGRADIALLY SPACED INWARDLY OF THE CYLINDRICAL WAL OF THE HOUSING, SAIDIMPELLER HAVING A REAR SHROUD AXIALLY SPACED FROM SAID INTAKE SHROUD ANDHAVING AN OUTER PERIPHERY SPACED RADIALLY INWARDLY FROM SAID WALL OF THEHOUSING; BLADES SUPPORTED BETWEEN SAID SHROUDS AND HAVING OUTERPERIPHERY EDGES EXTENDING BETWEEN THE SHROUDS ADJACENT THE PERIPERHYTHEREOF; ANNULAR WALL MEANS SUPPORTED WITHIN SAID HOUSING AND SPACEDRADIALLY INWARDLY FROM THE CYLINDRICAL WALL AND EXTENDING AXIALLYREARWARDLY FROM ADJACENT TO SAID REAR IMPELLER SHROUD, SAID ANNULAR WALLMEANS AND SAID CYLINDRICAL WALL DEFINING AN AXIALLY EXTENDING CHAMBERTERMINATING IN SAID DISCHARGE OPENING; SHAFT MEANS AND MEANS SUPPORTINGSHAFT MEANS WITHIN SAID HOUSING, SAID SHAFT MEANS ROTATABLY SUPPORTINGTHE IMPELLER; MEANS ON SAID SHAFT MEANS TO ROTATE SAID IMPELLER WHEREBYTHE CENTRIFUGED FLUID ENGAGEMENT SAID CYLINDRICAL WALL OF SAID HOUSINGDIVIDES INTO A MAJOR PORTION FLOWING INTO SAID ANNULAR CHAMBER AND AMINOR PORTION FLOWING INTO SAID SWIRL CHAMBER; SAID CYLINDRICAL HOUSINGWALL HAVING A PLURALITY OF SHORT, SUBSTANTIALLY FLAT AND SUBSTANTIALLYRADIALLY INWARDLY EXTENDING FLAPS MOUNTED THEREON, EACH OF SAID FLAPSHAVING A FREE INNER EDGE THAT TERMINATES SPACED RADIALLY OUTWARDLY OFTHE BLADES'' OUTER EDGES, EACH OF SAID FLAPS HAVING A PAIR OF AXIALLYSPACED END PORTIONS ONE THEREOF EXTENDING INTO SAID SWIRL CHAMBER ANDTHE OTHER PORTION EXTENDING ONLY OVER THAT PORTION OF THE OUTER EDGES OFTHE BLADES ADJACENT THE INTAKE SHROUD, SAID FLAPS BEING SO POSITIONED TOREDUCE TURBULENCE IN THE ZONE OF SEPARATION OF THE CENTRIFUGED FLUID ASIT FLOWS INTO SAID SWIRL CHAMBER, AND INTO SAID ANNULAR CHAMBER FROM THEZONE OF SEPARATION OF SAID MAJOR AND MINOR PORTIONS OF FLUID FLOW.